Mental Exam

The disability people want me to take a mental exam.  It will be in August.  I wonder what they'll find.   I have had my share of mental problems starting in high school when I flew off the handle in front of the whole school and don't remember what I did.  A similar incident happened after my sophomore year of college, and I was discharged from the air force without finishing basic training because of psychological issues a few months later.  Since then, there have been 3 suicide attempts, the latest a couple of weeks ago.  My short time in the state mental hospital seeing my fellow patients has me wondering how many people have mental problems that no one notices?  Most of the patients in my group didn't display their problems.  They looked and  acted "normal".  Most people that are around me wouldn't know I have a problem.  They might notice I have an odd way at looking at life and a weird sense of humor, but I brag about that.  There are some physical reasons for mental problems.  One that I suspect for me is my lack of sleep due to apnea and a bad cpap machine.  This came up after I was diagnosed with apnea.  I had been averaging depression incidents about 6 times of year for several years, but they stopped after getting on the machine.  My doctor said it was probably a low level of oxygen in my brain from the apnea.  How many people have problems they don't know about?  How can we notice them and possible help them?  And would you take the first step to get them help?